Stents are used for permanent or also only temporary splinting of body conduits that have become occluded or constricted as a result of stenosis.
The stents have a tubular metal supporting structure consisting of several annular segments. These are formed from segment struts continuously adjoining one another via transition sections. Annular segments adjacent to one another in the longitudinal axis of the stent are coupled by connector struts.
The stents are introduced into the intracorporal vessel by catheter techniques or by using similar insertion aids and are positioned in the area of the stenosis, the supporting structure being able to expand from a contracted insertion state to a supporting state of suitably increased diameter. This expansion can take place automatically in what are called self-expanding stents, but it can also be effected with the aid of a suitable instrument, for example a balloon catheter. In the vessel, the stents function as vascular prostheses for supporting the inside walls of the vessel.
In many applications, for example when used as a biliary stent in the bile ducts, the stent has to be removed again after it has been in the body conduit for a relatively short time, for instance a few months. This is normally done by pulling the stent back into a catheter. The diameter of the expanded stent, sometimes covered with bodily secretions or the like, has to be reduced again. For this, it is desirable that no aspect of the stent geometry gets in the way of pulling it back into a catheter of smaller diameter.
It would therefore be advantageous to provide a stent which, having good compatibility with the vessels in the supporting state, possesses a sufficiently high degree of flexibility and can be easily contracted in order to remove it from a body conduit.